This invention relates to slant axis rotary mechanisms, such as slant axis rotary engines and, more particularly, to the provision in such mechanisms of means for compensating for rotor deflection relative to the housing during operation so as to maximize compression ratios attainable and achieve maximum efficiency of operation.
In slant axis rotary mchanisms, such as a slant axis rotary engine, it is highly desirable to minimize the clearance between rotor parts and the walls of the operating chamber defined by the housing when the rotor is in a so-called "top dead center position". A frequent goal is to maintain such clearances in the range of 0.13 to 0.26 mm. Such clearances are difficult to achieve due to high gas pressures in the mechanism, particularly when the pressures are enhanced by combustion when the mechanism is used as an engine. For example, when a typical operating pressure as, 1200 psi, is present, one can reliably expect the presence of a 0.05 mm deflection in the housing, an identical deflection in the rotor in an axial direction and in the rotor thrust bearing structure. A deflection of approximately half the foregoing magnitude will occur in the shaft and the shaft thrust bearing housing. A deflection of approximately one-fourth of the housing deflection can be expected at the thrust bearing collar of the shaft.
Consequently, a total deflection on the order of 0.21 mm. will occur each time the mechanism is fired. Since, in slant axis rotary engines, firing occurs on both sides of a rotor flange, such movement will occur to each side of the mean rotor position.
For a lesser situation, when, for example, such a mechanism is employed as an engine and is idling, the gas pressures are lower and a total of approximately 0.14 mm deflection is present.
Thus, the deflections due to gas pressure are of the same magnitude as the minimum design clearance desired. As a consequence, interference between the rotor and the housing will not occur only if the parts are perfectly fabricated, that is, manufacturing tolerances are zero. Since a manufacturing tolerance equal to zero is impossible, in a practical sense, to achieve, it has heretofore been necessary to operate outside of the desired minimum clearance range with the consequence that compression ratios are lowered and parasitic volume is increased. Thus, mechanism efficiency is similary decreased.